<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        .big{
            border: 1px solid #333;
            width:300px;
            height: 300px;
            display: flex;
            flex-direction: row;
            background: yellow;
        }
        .child1{
            width:50px;
            height: 50px;
            background: red;
        }
        .child2{
            width:50px;
            height: 50px;
            background: blue;
            margin-right: auto;
        }
        .child3{
            width:50px;
            height: 50px;
            background: green;
            align-self: flex-end;
        }
        .child4{
            width:50px;
            height: 50px;
            background: pink;
           
        }

    </style>
</head>
<body>
    <div class="big">
        <div class="child1"></div>
        <div class="child2"></div>
        <div class="child3"></div>
        <div class="child4"></div>

    </div>
</body>
</html>